


Sinfully Sweet

by cielsdemon



Category: Kuroshitsuji | Black Butler
Genre: M/M, Smut, like 90 percent smut
Language: English
Status: Completed
Published: 2015-01-07
Updated: 2015-01-07
Packaged: 2018-03-06 12:20:19
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,345
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3134285
Author URL: https://archiveofourown.org/users/cielsdemon/pseuds/cielsdemon
Summary: <blockquote class="userstuff">
              <p>“Oh, Deidrich come off it,” Vincent groans without looking up from his book. “I’m not napping and you know it. I’m trying to read and you’re blocking all…of my…sun…” He trails off as he moves the book out of his line of vision. Instead of finding Diedrich in front of him scowling, Undertaker is standing before him with a wide smile across his pale features.</p><p>He cocks one hip to the side and tilts his head, allowing Vincent the chance to steal a glimpse of his face under the hair that falls in front of it. Most of his long hair is swept up in a ponytail and falls behind him in a long wave; only his fringe falls forward as usual, hiding his unique eyes from the rest of the world.</p>
            </blockquote>





	Sinfully Sweet

**Author's Note:**

  * For [kickcows](https://archiveofourown.org/users/kickcows/gifts).



> We had a 666 follower giveaway on our blog at the end of December and the fic winner wanted some Vincent/Undertaker goodness! Apologies for how long it took me to write... The holidays were busy and I am slow. I hope it's what you had in mind!
> 
> Enjoy!

“Oh, Deidrich come off it,” Vincent groans without looking up from his book. “I’m not napping and you know it. I’m trying to read and you’re blocking all…of my…sun…” He trails off as he moves the book out of his line of vision. Instead of finding Diedrich in front of him scowling, Undertaker is standing before him with a wide smile across his pale features.

 

He cocks one hip to the side and tilts his head, allowing Vincent the chance to steal a glimpse of his face under the hair that falls in front of it. Most of his long hair is swept up in a ponytail and falls behind him in a long wave; only his fringe falls forward as usual, hiding his unique eyes from the rest of the world.

 

"Should I even ask how you got that uniform?" Vincent asks, eyeing the checkered pants snug around Undertaker’s legs. Those lean, surprisingly sculpted muscles are usually hidden from view under long, flowing robes; it’s a genuine treat to get to see them outside of the bedroom.

 

"I have my ways," Undertaker sing-songs. "Plus, I doubt this'll be the last time I go undercover at this school." He squints up at the building and then grins in a way that makes Vincent’s stomach flip.

 

“Heaven forbid you not be one step ahead,” Vincent chuckles. “You received my message, then?”

 

"Of course.” He dismisses Vincent with a nonchalant wave of his hand. “I wouldn’t be here if I hadn’t. But you know I require payment, young Phantomhive."

 

Vincent raises an eyebrow and moves into a sitting position. "The usual?" he asks, a smirk flirting at the edges of his mouth.

 

"I was thinking of something a bit…sweeter, this time." Undertaker holds a hand out to the smug Phantomhive and pulls him upright.

 

When they’re face to face Vincent's smirk blooms into a full-blown grin, "Excellent."

 

~

 

“Here?” Undertaker’s voice rises incredulously as Vincent pulls him by his waistband behind a bookshelf. He was under the impression they snuck into the library for research, though that seems to be the furthest thing from Vincent’s mind. “Anyone could find us in here.”

 

Vincent laughs. His hands are already snaking around Undertaker’s waist and pulling him forward until their bodies are flush together with Vincent’s back against the books. “Where’s your sense of adventure?” He nips Undertaker’s lower lip and grins at him. “I’ve always wanted to do it in a library.”

 

“You’re a tricky one, Phantomhive,” Undertaker laughs. “I wouldn’t have pegged you for an exhibitionist.” His breath rushes out in a sigh against Vincent’s lips, teasing forgotten as he’s pulled forward again and insistently kissed.

 

Vincent kisses thoroughly, his lips and tongue mapping out the contours of Undertaker’s mouth as though he’ll be quizzed on them later. His tongue sweeps through Undertaker’s lips and curls, licking delicately at the point of a canine before it’s caught and bitten between Undertaker’s teeth.

 

“Hah.” Vincent huffs a breath in surprise and pulls back, hand lifting to delicately finger the tip of his tongue. Undertaker watches him with a smile that’s sharpened by the heat in his eyes.

 

“I wouldn’t have pegged you for a biter,” he counters, genuinely surprised. The sharp metallic taste in his mouth and the smear of red on his finger confirm it. Undertaker raises an eyebrow and surges forward to catch Vincent’s injured tongue and suck on it, causing Vincent’s breath to shudder out in a gasp that has Undertaker giggling against his skin.

 

“Really?” he hums, moving down to catch his teeth on the point of Vincent’s chin. “And here I was thinking you were clever, Phantomhive.”

 

Vincent laughs in response. The reaper does have a point; he should have been expecting this.

 

Undertaker tips his head as Vincent’s clever fingers pull the ribbon out of his hair; it falls down his back and Vincent buries his hands in it, tugging insistently to bring Undertaker closer to his neck. Undertaker goes easily enough, his fingers working open the knot of Vincent’s tie and tugging until it’s loosened and he can pull Vincent’s collar to the side and place his mouth on a larger area of skin.

 

With one hand still curled through Undertaker’s hair as he sucks marks into his neck, Vincent pushes the other between their bodies. His fingers barely fit in what little space is left between their hips, but he manages to twist and curl his fingers around the bulge in Undertaker’s trousers.

 

He squeezes and strokes slowly, reveling in the shiver he receives as his palm rubs over Undertaker’s length through the fabric of his pants.

 

“Ah, Phantomhive…”

 

Vincent hushes Undertaker with a kiss, their lips barely pulling apart long enough for him to murmur, “Quiet. We’re in a library.” He gives a wicked grin against Undertaker’s mouth and, in the next moment, has a hand down his pants. Vincent undoes them quickly and wraps his fingers around Undertaker’s cock.

 

As Vincent strokes, Undertaker groans, the noise muffled in their kiss, and he drags his fingers down Vincent’s chest, popping open buttons as he goes. His nails – trimmed slightly, but still long – drag faint pink lines down Vincent’s torso. His thumbnail circles his nipple and Vincent sucks in a sharp breath, his grip faltering.

 

Just as he manages to tighten his fingers and find his rhythm again, Undertaker pinches his nipple between two fingers and tugs. His nails drag down either side of the rosy bud and his knuckles pinch it, twisting gently until Vincent lets out a short cry and pants his name.

 

Undertaker smirks, lips a dangerous curve against Vincent’s ear. “Quiet,” he whispers, amusement lacing his words, “We’re in a library, Vincent.”

 

Vincent laughs lowly and rubs his thumb over the slit on Undertaker’s cock. “Is that how we’re going to play this?” He thumbs under the head slowly, dragging out each back and forth motion until Undertaker bucks forward into his grasp. “I could do this all day,” he whispers as he leans in to capture Undertaker’s plush lower lip between his teeth.

 

Undertaker gasps softly, a low sound not unlike a growl rumbling under his words. “Be careful what you wish for.” His words lose a little meaning as they come out breathy, heavily laced with want. Vincent smiles at him and kisses him again, this time making Undertaker tilt his head so he can kiss down his neck.

 

His mouth presses open and damp to the scar around Undertaker’s throat, tongue flitting out to trace over it until Undertaker moans in his ear. He bites delicately at Undertaker’s pulse point and trails his kisses down as his fingers leave Undertaker’s hair and pull his tie loose.

 

While Vincent’s mouth is busy tracing the contours of the scarring around his neck, Undertaker takes the initiative to undo Vincent’s trousers and slip his hand inside, seeking out the hard, hot curve of flesh just begging to be touched.

 

The inside of Vincent’s pants is damp, warm from the steady leak of precome that speaks to how badly he wants this. He pants harshly against Undertaker’s collarbone, fingers stilling on his partner’s cock as his attention focuses on the slick pull of Undertaker’s hand on his own hard length.

 

“Ah, you… Hah…” Vincent struggles to form words as Undertaker bats his fingers away from his cock and slides them together. “Ohh,” is an exhaled breath against Undertaker’s shoulder, and Vincent mashes his lips to his partner’s skin in an effort to quiet himself as Undertaker rolls his hips forward.

 

A hand curves around Vincent’s thigh and pulls upward, guiding him into rising up on balls of his feet. Their hips now fit perfectly together, though Vincent isn’t sure how long he’s going to be able to stand like this.

 

Undertaker laughs gently against his ear, and a lilting, “Little Phantomhive,” accompanies the huff of amusement. Vincent grunts at him, cheeks hot, but Undertaker wraps his hand around their cocks and strokes them together, effectively silencing any retort Vincent could have thought up.

 

Vincent pushes a hand down between them again and wraps his fingers around Undertaker’s, squeezing and making the space they’re fucking into that much tighter. He tips his head, teeth catching the metal end of one of Undertaker’s ear piercings and tugging sharply. Undertaker moans and his hips jerk forward, throwing off their rhythm.

 

Undertaker’s head falls forward against Vincent’s shoulder and Vincent takes the opportunity to put his mouth back on Undertaker’s skin. He bites sharply at the curve where neck and shoulder meet, then gentles his mouth as he moves his attention upward. By the time he’s pressing kisses and licks to the underside of Undertaker’s jaw, his lips are barely touching him.

 

He licks at the curve of Undertaker’s jaw and kisses him there, tongue catching the salt of sweat on his skin as he drags his mouth back down. Undertaker shudders against him, the hand resting on his chest twitching and sliding to grip the curve of Vincent’s waist.

 

In response, Vincent squeezes his fingers around their cocks and that squeeze, accompanied with a delicate scrape of teeth across his pulse, sends Undertaker over the edge. His hips surge forward in a series of fluid rolls as he spends across their hands. Vincent strokes him through it, abandoning his own pleasure to ease Undertaker through his.

 

Vincent kisses absently at the side of Undertaker’s head, lips pressing into the silky thickness of his hair. He grins, only slightly smug, when Undertaker turns his head and blindly seeks out the warmth of his mouth.

 

They kiss languidly, tongues slicking past each other to explore the damp heat of each other’s’ mouths. Vincent breaks the kiss first, pulling away with a sigh to glance down between their bodies. “Ah, Undertaker…”

 

Before the name has fully left his lips, the man in question is pulling back and straightening his clothes. In an instant, Undertaker looks as put together as when he arrived, save for his mussed hair. Vincent watches in confusion, brows furrowed, puffy lips pursed. “Um.”

 

“Hush, Phantomhive,” Undertaker says with a huff of a laugh. “When have I ever left you wanting?” He has a point. Vincent smiles and tilts his hips slightly, shifting so he’s leaning back against the bookshelf.

 

His fingers wind their way into Undertaker’s hair as the reaper sinks to his knees. Undertaker glances up at him through the fall of silver hair and smiles, his lips just a breath away from the damp head of Vincent’s cock. “I told you I wanted something sweeter, didn’t I?” He wraps his lips around the crown of Vincent’s cock and sucks precome away with a soft pop. “This will do.”

 

Vincent moans as Undertaker guides his cock between his lips. A sharp glance from under thick lashes reminds him where they are and he slaps a hand over his mouth to muffle any further sounds of pleasure.

 

Much to Vincent’s dismay, it seems Undertaker wants to take his time with him; his long fingers circle the width of Vincent’s cock and stroke up slowly from the base to where his lips are suctioned tightly around the head. He repeats this several times until Vincent is squirming, hips making aborted thrusts forward into the heat of Undertaker’s mouth.

 

“Under…taker,” Vincent groans, hand abandoning his mouth to push through Undertaker’s hair and attempt to drag him forward.

 

Undertaker pulls away with a slight shake of his head. “Ah, ah, ah,” he scolds, lips upturned in a teasing smile. “What’s the magic word?” he sing-songs.

 

Vincent squints and shifts his weight, hips nudging forward. Undertaker sweeps his hair out of his face with one hand and raises his eyebrows expectantly. Too close to the edge to bother with dragging this out, Vincent exhales a heavy sigh and meets Undertaker’s eyes. “Please.”

 

Undertaker giggles happily and lowers his head to swirl his tongue through the pearl of precome on to the tip of Vincent’s cock. He sucks once, playful, and then swallows Vincent to the hilt without hesitation.

 

Vincent doubles over with a gasp, hands fisting in Undertaker’s hair, head swimming. “Oh my fu – Undertaker, ah…” Undertaker gives a low hum around the appendage in his mouth and slides his tongue up, tickling it just under the head until Vincent keens.

 

With a wet slurp, Undertaker pulls nearly all the way off and suckles; his tongue laves over the slit, coaxing precome to bead up and fall into his waiting mouth. Vincent moans, hips twitching forward despite Undertaker’s hands holding his body in place.

 

“I’m gonna,” Vincent warns, voice high and desperate. As if he hasn’t spoken – or maybe because he has – Undertaker drags his cock through the plush pucker of his lips and sucks deliberately, his tongue working around the head as he swallows him back down.

 

Vincent’s hips jerk forward and he cries out, just barely remembering to slap a hand over his mouth to muffle the sound as his orgasm takes him over. His toes curl in his shoes and he grips Undertaker’s hair in his fist hard enough to hurt. Undertaker doesn’t seem bothered as he bobs his head, milking Vincent for every last drop.

 

When Vincent’s muffled moans have quieted and his fingers have released their death grip, Undertaker slowly pulls back and licks his lips. He sucks his bottom lip between his teeth and smiles up at Vincent, head cocked.

 

“Very sweet indeed,” he chuckles, nimble fingers tucking Vincent back into his trousers. He rises to his feet smoothly and Vincent gapes at him as he fixes his hair, tying it easily back up into a ponytail. “Hmm?” he asks when he realizes Vincent is staring at him.

 

Vincent’s mouth twists with a smile and he shakes his head, one elbow pushing against the bookshelf to right himself. “Nothing. I think next time I’d like to be the one to debauch you.” He pulls his shirt together and starts closing the buttons as Undertaker laughs.

 

“Next time, hm? I’ll be looking forward to that.”

**Author's Note:**

> You know by now. Come join us on our [blog](http://cielsbitch.tumblr.com/)!


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